Magnetic recording involves mechanical motion between the media and the heads in which the spacing between these components must be made critically small. In rigid-disk drives, a magnetic core element is mounted on a slider which flies above the rotating disk. Very often, the core element and slider are manufactured such that the entire head is monolithic. The slider portion is generally designed to create hydrodynamic pressure and weight the head to achieve a flying height barely above the disk surface (typically on the order of 10 microinches or less).
Most magnetic recording heads in use today are based upon the familiar inductive coil and magnetic core head design which is well-known in the art. The general trend in development has been to require smaller dimensions in gap length, track width, and core geometry to satisfy the increasing demand for higher recording densities and bandwidths. There are also corresponding competitive pressures to produce a head as inexpensively as possible. As head size shrinks and performance is enhanced, the durability of various head elements to physical and mechanical stresses becomes critical. Thus, what is needed is a strong, durable and low-cost magnetic recording head having minimized gap dimensions.
The gap in a recording head is designed to produce a field amplitude capable of recording the storage media. The core geometry and materials are designed to provide adequate field strength at the signal frequency along the direction of the media motion in order to maximize the recording efficiency. Magnetic flux is delivered to the gap by a magnetic core element having a wire coil wrapped radially around one of the poles of the core. The wire coil around the core is usually designed to be close to the gap to improve the efficiency of the inductive coupling between the coil and the poles of the gap.
One widely utilized magnetic head has a core structure shaped like a "C", often referred to as a "C-bar" design. FIG. 1 shows a magnetic recording head having a C-bar core member. An enlarged view of the C-bar structure is also shown in FIG. 2a.
Several problems have been associated with the C-bar head design. For instance, because one pole of the C-bar structure protrudes outward from the slider portion of the head it is especially prone to fracture or breakage. This most frequently occurs during the manufacturing process. Usually, both the slider and core are manufactured out of a ferrite material. The brittle nature of ferrite and the ever shrinking dimensions of the magnetic head exacerbate the problem of breakage, making the C-bar magnetic head design expensive to manufacture as well as reducing recording head manufacturing yields.
Another problem associated with the C-bar structure has to do with the edges of the core pole in the area where the writing coil is wrapped. Since these edges are square, they have a tendency to cut into the wire coils degrading head performance. As a result, these edges must be rounded at some point in the manufacturing process. Typically, this involves sanding of the edges of the C-bar core by hand; a process which is called "blending". Due to the fragile nature of the C-bar, blending is another source of yield loss which may occur.
Yet another problem with the C-bar structure involves the bottom rail used to form one pole of the recording gap. In the C-bar device, this rail extends outward from the slider body. Because the rail is unsupported, it is easily cracked or broken off.
Therefore, what is needed is a high-performance, mechanically resilient recording head which and is relatively inexpensive to manufacture. As will be seen, the present invention provides a high performance, low-cost magnetic recording head which is well suited for rigid-disk applications. The head of the present invention employs an I-bar shaped magnetic core element which is more durable and better performing than the prior art C-bar head.